There are already known various devices permitting the generation of a “cold” plasma (that is to say at ambient temperature and pressure) by dielectric barrier discharge (DBD) between two electrodes coated with an insulating material, between which a gas stream (for example of helium, argon or nitrogen) is made to flow.
In a first type of known solution (see, for example, Laroussi et al., (2005), Applied Physics Letters, 87, 986-987; “Room-temperature atmospheric pressure plasma plume for biomedical applications”), such a device comprises two electrodes which are subjected to a potential difference and through which there passes a stream of argon having a displacement speed estimated at 8 m/s. Such a solution presupposes the provision of means for storing argon under pressure and for introducing a stream of argon which flows between the two electrodes. In particular, such a solution presents practical problems associated with the use of a gas under pressure and does not permit the production of a self-projected atmospheric air plasma at ambient pressure and temperature.
A second type of known solution, similar to the preceding solution, consists in forming a plasma of the “corona plasma” type between two coaxial electrodes separated by a volume of insulating gas.
The document Pointu et al. (2005) (Pointu A. M., Ricard A., Dodet B., Odic E., Larbre J. and Petchu M. G., (2005), J. Phys. D Appl. Phys. 38, 1905-1909; “Production of active species in N2—O2 flowing post-discharges at atmospheric pressure for sterilization”) describes a process for sterilization by means of a cold plasma produced during the treatment of a preformed gas stream of nitrogen and oxygen with a 10 kHz pulsed corona discharge generated between two electrodes. Such a sterilization process requires external means for forming a gas stream. Nor does it permit the production of a self-projected plasma from the atmospheric air at atmospheric pressure.
U.S. Pat. No. 7,229,589 describes a decontamination process for a surface, in which a stream of molecular nitrogen previously stored under pressure is subjected to a pulsed discharge in order to treat the gas stream with discontinuous discharges. Such a decontamination process requires means for preparing molecular nitrogen of high purity and for pressurizing it prior to the decontamination treatment, and does not permit the generation of a self-projected plasma jet from atmospheric air at atmospheric pressure.